<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
        <title></title>
        <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
        <meta content="telephone=no" name="format-detection">
        <script>
            var fun = function (doc, win) {
                var docEl = doc.documentElement,
                    resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
                    recalc = function () {
                        var clientWidth = docEl.clientWidth;
                        if (!clientWidth) return;

                        //这里是假设在750px宽度设计稿的情况下，1rem = 75px；
                        //可以根据实际需要修改
                        docEl.style.fontSize = 75 * (clientWidth / 750) + 'px';
                    };
                if (!doc.addEventListener) return;
                win.addEventListener(resizeEvt, recalc, false);
                doc.addEventListener('DOMContentLoaded', recalc, false);
            }
            fun(document, window);
        </script>
        <style type="text/css">
            body,div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,form,fieldset,input,textarea,p,blockquote,th,td {
                margin:0;
                padding:0;
            }
            table {
                border-collapse:collapse;
                border-spacing:0;
            }
            fieldset,img {
                border:0;
            }
            address,caption,cite,code,dfn,em,strong,th,var {
                font-style:normal;
                font-weight:normal;
            }
            ol,ul {
                list-style:none;
            }
            caption,th {
                text-align:left;
            }
            h1,h2,h3,h4,h5,h6 {
                font-size:100%;
                font-weight:normal;
            }
            q:before,q:after {
                content:'';
            }
            abbr,acronym { 
                border:0;
            }
			.app {
                width: 9rem;
                height: 10rem;
                background: #999;
            }
			.app2 {
                width: 90%;
                height: 10rem;
                background: #333;
            }
		</style>
	</head>
	<body >
        <div class="app"></div>
        <div class="app2"></div>
	</body>
</html>